PUSCH Beam Management With Mixed SRS Modes in Dense Deployments
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Solution Overview
Problem
In dense deployment scenarios with both TRPs and RPs, efficiently managing UL beams for UEs with beam correspondence capability is challenging, as DL-based UL beam management is not feasible for RPs due to the absence of DL RS, leading to inefficient resource usage and increased interference.
Innovation Solution
A dynamic switching mechanism between codebook-based and non-codebook-based UL transmission is introduced, using DCI-based indicators to switch between modes without requiring additional DCI fields, and configuring UEs with mixed SRS resource sets to support both TRPs and RPs, optimizing SRS transmission for beam management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DL-based UL beam management is used for TRPs, then UL transmission efficiency is improved, but it cannot be applied to RPs due to absence of DL RS
Solution Approach 1:
The system segments beam management approaches by reception point type: DL-based beam management is applied to TRPs where DL RS is available, while SRS-based beam management is applied to RPs where DL RS is absent. This segmentation allows each reception point to use the most appropriate beam management method for its characteristics.
Solution Approach 2:
SRS (Sounding Reference Signal) serves as an intermediary mechanism for RPs to perform beam management without DL RS. The UE transmits SRS to RP, and the RP uses this uplink signal to determine optimal receive beams, compensating for the absence of downlink reference signals.
2Adaptability or versatility
If separate SRS resource sets are configured for codebook-based and non-codebook-based operation, then transmission mode flexibility is improved, but device complexity and configuration overhead increase
Solution Approach 1:
The patent merges codebook-based and non-codebook-based SRS resources into a single unified SRS resource set. This unified set contains both types of SRS resources, allowing the network to dynamically select which resources to use based on the desired transmission mode, thereby reducing configuration overhead while maintaining flexibility.
Solution Approach 2:
The unified SRS resource set serves multiple functions: it supports both codebook-based and non-codebook-based transmission modes, and can be used for both beam management and uplink channel sounding. This multi-functionality reduces the need for separate dedicated resource sets.
3Reliability
If SRS transmission is performed for all directions including DL-based UL directions, then beam management coverage is improved, but resource efficiency decreases and interference increases
Solution Approach 1:
The system extracts and removes SRS transmission requirements for directions already covered by DL-based UL beam management. Since TRPs use DL-based methods, SRS transmissions targeted at TRPs are eliminated, reducing unnecessary resource usage and interference while maintaining complete beam management coverage through RP-directed SRS transmissions.
Data Source
AI summary
A user equipment (UE) in a wireless network may receive Downlink Control Information (DCI) that schedules Physical Uplink Shared Channel (PUSCH) for non-codebook-based and/or codebook-based PUSCH operation. The UE may be configured with a Sounding Reference Signal (SRS) resource set for each codebook-based operation and non-codebook-based operation. The UE may transmit using a codebook base operation in a first set of PUSCH occasions and transmit using a non-codebook-based operation in a second set of PUSCH occasions. The DCI may include multiple SRS Resource Indicator (SRI) fields pertaining to different sets of PUSCH occasions. Similarly, DCI may include information pertaining to a number of layers for precoding for a set of PUSCH occasions.